In the art of audio sound reproduction it is well-known that the dynamic loudspeaker is more nonlinear and generates more distortion than all the other system components combined. This problem is particularly severe with smaller less expensive speakers at low frequencies which require large volume velocities and long cone excursions. As the cone displacement increases the stiffness of both the inner spider and the outer surround increases rapidly resulting in a nonlinear suspension compliance generating high distortion. Another major source of loudspeaker distortion is the nonuniformity of flux density in the magnet gap and the resulting decrease in the BL force factor as the voice-coil moves from its initial rest position.
For example, in a typical small inexpensive sound system at a frequency of about 50 Hz the total harmonic distortion of the amplifier might be of the order of 0.5%, whereas the distortion of the loudspeaker might well exceed 50.0%, depending upon the loudness. That is, the amplifier is almost linear, whereas the loudspeaker is extremely nonlinear with gross distortion quite evident to the ear. This vast difference is due in large part to the fact that the amplifier distortion is reduced by a large amount of negative feedback, whereas the conventional loudspeaker has no feedback whatever.